Influence of iron content on the structural and magnetic properties of Ni-Zn ferrite nanoparticles synthesized by PEG assisted sol-gel method

Ni-Zn ferrite nanoparticles of smaller particle size and high saturation magnetization have gained a special attention for their use in biomedical applications. The development of such nanoparticles requires rigorous processing conditions in arriving at desired characteristics. Ni-Zn ferrite nanoparticles of three different compositions Ni0.65Zn0.35Fe2O4, Ni0.65Zn0.40Fe1.95O4 and Ni0.60Zn0.35Fe2.05O4 containing varying amounts of iron concentration 50.00 mol%, 48.75 mol%, and 51.25 mol% respectively were processed by the sol-gel method using polyethylene glycol (PEG) as a chelating agent and characterized by techniques X-ray diffraction, Transmission electron microscopy, field emission scanning electron microscopy and Fourier transform infrared spectroscopy in elucidating the structural parameters. Ferrite compositions containing lower and higher iron content require the lower annealing temperature to produce higher saturation magnetization as compared to the stoichiometric composition. The composition of lower iron content favoured smaller particle size of 9 nm, while the material of higher iron content showed enhanced saturation magnetization of 91.9 emu/g. From the knowledge of literature and our previous works, it is opined that no other chelating agent than PEG proved to be an efficient one in controlling the particle size and improving the microstructure.